The difference between past performance and experience is simple. Experience evaluates whether your company in the past did something relevant to the upcoming government contract. Past performance evaluates how well your company performed, not just whether it did something.
If experience is a record of your attendance at school, past performance is the report card. If experience is your diploma, past performance is your actual grade point average.
What if I have no past performance?
The government can use past performance and experience as evaluation factors. If the government uses past performance, a special government rule allows your company to compete despite having no past performance.
The government wants to encourage newcomers, so a special rule states that a potential contractor with no past performance cannot be rated favorably or unfavorably on past performance. The potential contractor with no past performance must receive some sort of neutral rating on past performance.
Keep in mind that your competitors with excellent past performance retain an advantage. This special rule keeps your company from being disqualified completely. In the final decision, the government can value a positive rating on past performance more than a neutral or nonexistent rating on past performance.
What if I have no experience?
Unfortunately for you, some government contracting officers discovered a clever way to circumvent this rule. There is no saving grace for the contractor who lacks both past performance and experience. By using the evaluation factor of experience, the government can effectively discriminate against contractors with no experience.
Can I use past performance from the private sector?
You need to read the solicitation to know whether your company can use past performance from the private sector or nongovernment contracts. Sometimes you can and sometimes you cannot. The government has flexibility in how it can evaluate past performance. So, the government is free to restrict its evaluation of past performance to government contracts only. Instead, the government can open past performance evaluation to both government contracts and private sector contracts. If there is no clear distinction, submit a formal question to the contracting officer.
~Free excerpt from Government Contracts in Plain English: https://www.amazon.com/dp/173419815X/ and Federal Acquisition Regulation in Plain English: https://www.amazon.com/dp/1734198117/